Some basic crypto laid down and tests

kordophone/Crypto/NSData+AES.h

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+//
+//  NSData+AES.h
+//  MessagesBridge
+//
+//  Created by James Magahern on 11/15/18.
+//  Copyright © 2018 James Magahern. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import <CommonCrypto/CommonCrypto.h>
+
+@interface NSData (AES)
+
+- (NSData *)encryptedDataWithKey:(NSData *)key iv:(NSData *)iv error:(NSError **)error;
+- (NSData *)decryptedDataWithKey:(NSData *)key iv:(NSData *)iv error:(NSError **)error;
+
+@end

kordophone/Crypto/NSData+AES.m

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+//
+//  NSData+AES.m
+//  MessagesBridge
+//
+//  Created by James Magahern on 11/15/18.
+//  Copyright © 2018 James Magahern. All rights reserved.
+//
+
+#import "NSData+AES.h"
+
+@implementation NSData (AES)
+
++ (NSData *)AES128Operation:(CCOperation)operation
+              withInputData:(NSData *)inputData
+                        key:(NSData *)key
+                         iv:(NSData *)iv
+                      error:(NSError **)error
+{
+    size_t dataMoved = 0;
+    NSMutableData *outputData = [NSMutableData dataWithLength:(inputData.length + kCCBlockSizeAES128)];
+    CCCryptorStatus status = CCCrypt(
+        operation,
+        kCCAlgorithmAES,
+        kCCOptionPKCS7Padding,
+        key.bytes,
+        key.length,
+        iv.bytes,
+        inputData.bytes,
+        inputData.length,
+        outputData.mutableBytes,
+        outputData.length,
+        &dataMoved
+    );
+    
+    if (status == kCCSuccess) {
+        outputData.length = dataMoved;
+    } else {
+        *error = [NSError errorWithDomain:@"CommonCryptoError"
+                                     code:status
+                                 userInfo:nil];
+        
+        outputData = nil;
+    }
+    
+    return outputData;
+}
+
+- (NSData *)encryptedDataWithKey:(NSData *)key iv:(NSData *)iv error:(NSError *__autoreleasing *)error
+{
+    return [[self class] AES128Operation:kCCEncrypt withInputData:self key:key iv:iv error:error];
+}
+
+- (NSData *)decryptedDataWithKey:(NSData *)key iv:(NSData *)iv error:(NSError *__autoreleasing *)error
+{
+    return [[self class] AES128Operation:kCCDecrypt withInputData:self key:key iv:iv error:error];
+}
+
+@end